zombie process

(Or "defunct process") A Unixprocess
that has terminated (either because it has been killed by a
signal or because it has called exit()) and whose parent
process has not yet received notification of its termination
by executing (some form of) the wait() system call.

A zombie process exists solely as a process table entry and
consumes no other resources. This entry is retained to hold
the child's exit status until the parent process wants to
retrieve it. The parent can also be notified asynchronously
via a signal of the child's termination.

Zombie processes can be seen in "ps" listings occasionally
(with a status "Z" in some versions).